Safety relief valve structure for railway cars

ABSTRACT

A safety relief valve structure for a railway car having an enclosed shell which is adapted to be placed under an internal fluid pressure, especially for unloading particulate lading. A pilot-operated safety valve on the car has a main valve inlet communicating directly with the interior of the car, and a separate pilot line provides fluid communication between the interior of the car and the safety relief valve for controlling the operation of the valve. A filter is positioned in the separate pilot line and minimizes any passage of air entrained lading to the safety valve through the pilot line. The filter comprises a housing and a filter element within the housing through which the air and any entrained lading particles pass. The filter element has a micron rating between around five and 25 to entrap lading particles of a micron size greater than the micron rating of the filter element.

United States Patent [72] Inventors Dallas W. Rollins St. Charles;Richard II. Dugge, St. Louis, both of Mo. [21] Appl. No. 857,098 [22]Filed Sept. 11, 1969 [45] Patented Dec. 14, 1971 [73] Assignee ACFIndustries, Incorporated New York, N.Y.

[54] SAFETY RELIEF VALVE STRUCTURE FOR RAILWAY CARS 1 Claim, 4 DrawingFigs.

[52] US. Cl 302/53, 302/52, 137/489 [51 Int. Cl B65g 53/40 [50] Field ofSearch 302/53, 52; 137/489; 251/44 [56] References Cited UNITED STATESPATENTS 1,228,104 5/1917 Fulton 137/489 1,719,686 7/1929 Browne 137/4893,438,682 4/1969 Mohrhusen 302/52 3,469,888 9/1969 Aller et al. 302/52Primary Examiner-Harvey C. Hornsby Assistant ExaminerMerle F. MaffeiAllomeyEugene N. Riddle lading. A pilot-operated safety valve on the carhas a main valve inlet communicating directly with the interior of thecar, and a separate pilot line provides fluid communication between theinterior of the car and the safety relief valve for controlling theoperation of the valve. A filter is positioned in the separate pilotline and minimizes any passage of air entrained lading to the safetyvalve through the pilot line. The filter comprises a housing and afilter element within the housing through which the air and anyentrained lading particles pass. The filter element has a micron ratingbetween around five and 25 to entrap lading particles of a micron sizegreater than the micron rating of the filter element.

PATENTED HEB] 41s" SHEET 1 [IF 2 INVENTORS.

DALLAS W. ROLLINS RICHARD H. DUGGE ATTORNEY SAFETY RELIEF VALVESTRUCTURE FOR RAILWAY CARS BACKGROUND OF THE INVENTION Conventionalsafety valves for covered hopper railway cars, especially when employedwith particulate lading, such as cement or flour, are subject toclogging of the working parts of the valve from lading contamination andwear on the valve seat upon the blowing of the lading from the valveduring operation of the safety relief valve. Thus, especially afterprolonged use with a railway covered hopper car in which particulatelading is being carried and unloaded by pressurizing the interior of thecar, valve members are not apt to seat properly in many instances andthe working parts may not function adequately in many instances becauseof lading contamination.

DESCRIPTION OF THE INVENTION The present invention is directed to asafety relief valve structure for a railway car having an enclosed shellwhich is subjected to internal fluid pressure, especially for unloadingparticulate lading, such as cement or the like. A pilot-operated safetyrelief valve is provided which has the pilot portion and all workingparts of the valve completely sealed from the valve main inlet to theinterior of the car. The safety valve has a fluid control chamber formedbetween a main diaphragm across the main inlet and a control diaphragmin a spaced generally parallel relation to the main diaphragm. A smallpilot line which senses the pressure of the car is in fluidcommunication with the fluid control chamber to provide a pressuretherein corresponding to that of the interior of the car. To prevent thepilot line from permitting the passage of particulate particles into thesafety relief valve, a filter is placed within the pilot air line andcomprises a filter element having a micron rating of between around 5and 25 microns with a filtration area of 50 to I square inches. Such afilter element ensures that only lading particles smaller than that ofthe micron rating of the filter will pass into the valve. Micron ratingsbelow or microns which may pass through the valve should not affect theoperation of the valve or result in particles clogging the valve. Byutilizing a separate pilot line and a separate control diaphragm, a veryeffective reseating of the main diaphragm is provided. The valve may beset to be actuated upon an internal pressure of 6 p.s.i., for example,being reached within the interior of the car, and will reseat itselfwhen the pressure within the car is lowered to around 5% or 5% p.s.i.The main diaphragm valve has a minimum of chatter and has a seat whichwill not deteriorate from the friction of lading or valve chatter.

The invention accordingly comprises the constructions hereinafterdescribed, the scope of the invention being indicated in the followingclaims.

ln the accompanying drawings, in which one of various possibleembodiments of the invention is illustrated,

FIG. 1 is a section of a covered hopper railway car having a safetyrelief valve structure comprising the present invention positioned onthe roof thereof and communicating with the interior of the car;

FIG. 2 is an enlarged partial top plan of the roof showing the valvestructure thereon;

FIG. 3 is a sectional view of the specific safety relief valve employedin the safety valve structure of the present invention; and

FIG. 4 is a section of the filter means positioned in the pilot line ofthe safety valve structure comprising the present invention.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

Referring now to the drawings for a better understanding of thisinvention, a covered hopper railway car is generally indicated l0 andhas sides 12 connected by a roof I4. Hopper 10 has a bottom dischargeoutlet 16 for the pneumatic discharge of lading, such as flour orcement, from the car at an unloading site. Normally, railway car 10 isnot pressurized in transit but is pressurized at the unloading site forunloading pneumatically the material in a suitable storage structure orhighway vehicle adjacent the track. For unloading, a source of air isconnected to the car and the car is pressurized to an internal fluidpressure of around 5 p.s.i., for example. Then, a suitable unloadinghose is connected to the outlet and the lading is drawn from theinterior of the car. For further details of the unloading system,reference is made to US. Pat. No. 3,302,979 dated Feb. 7, 1967, theentire disclosure of which is incorporated by this reference.

The safety valve structure comprising the present invention is generallyindicated 30 and is positioned on the upper portion of roof 14. An inletpipe 32 has its lower end within the interior of car 10 and has itsupper end connected directly to a safety relief valve generallyindicated 34. A pilot bypass line 36 has an inlet 38 adjacent one endthereof communicating with the interior of the car and has its other endconnected to safety valve 34 at 40.

Mounted within bypass line 36 and comprising an important part of thisinvention is a filter structure generally indicated 42. Filter structure42 comprises a base 43 having an inlet 44 and an outlet 46. A removablehousing 48 is threaded onto base 52 to permit a filter element orcartridge 54 to be removably positioned therein. Filter element 54 isgenerally cylindrical in shape and has a central bore 56 therethrough.Air and entrained lading enter inlet 44 from bypass line 36. The airflows through filter element 54 into the central bore 56 thereof and outthrough outlet 46 leaving any lading or foreign matter embedded withfilter element 54. Thus, filter element 54 removes lading from the airwhich enters the pilot line. Filter element 54 may preferably have amicron rating of between around 5 and 25 with a filtration area ofbetween around 50 and mo square inches. Thus, particles down to 5 or 10microns in size will be entrapped in filter element 54. Lading particlessmaller than 5 or 10 microns will pass through the filter structure 42and will not affect the operation of safety valve 34 due to their smallparticle size. A relatively large filtration area is required to provideadequate life for the filter and to reduce the pressure drop of thefluid pressure moving through bypass line 36 to valve 34. If thepressure drop is too great, the sensitivity of valve 34 will be affectedand might not reseat as fast as desirable. The filter element orcartridge may be of cotton, Dynel, polypropylene, Orlon, nylon, or glassfibers with a micron rating of between 5 and 25.

Safety relief valve 34 comprises a base 60 having inlet 32 threadedthereon and communicating with the interior of car 10. Valve seat 62 hasa main diaphragm 64 seated thereon. Diaphragm 64 is normally urged intoseated engagement on seat 62 by spring 66. Spring 66 is compressedbetween spring seat 68 carried by diaphragm 64 and a stud 70 on valvecover 71. Upon unseating of main diaphragm 64, vents 72 in base 60permit the air and entrained lading to be vented to atmosphere.

A fluid control chamber 73 is provided between main diaphragm 64 and apilot-controlled diaphragm 74. Control diaphragm 74 is clamped betweenvalve cover 71 and a spring housing 76 by studs 78. A control spring 80is biased between a lower valve seat 82 on control diaphragm 74 and anupper valve seat formed by an adjusting screw 84. Screw 84 may bemanually adjusted to control the bias of spring 80. A lock nut 86secures adjusting screw 84 in position. Air from bypass line 36 entersport 88 which is in fluid communication with control chamber 73 throughport 90. Thus, fluid control chamber 73 is in fluid communication withthe interior of car 10.

A lever 92 is pivoted at 94 to spring housing 76 and has one end 96fitting on the upper end of spring seat 82. The upper end of a pilotvalve 100 is contacted by the other end 98 of lever 92 at 102. A springretainer 104 houses a pilot valve spring 106 and upon a downwardmovement of lever end 98, valve 100 is unseated to relieve the pressurewithin the fluid control chamber 73.

ln operation, upon an internal pressure within the interior of car 10being reached which exceeds 6 p.s.i., for example, main diaphragm 64will be unseated to permit air and entrained lading to be vented orblown to atmosphere through vent ports 72. The pressure within fluidcontrol chamber 73 is responsive to the internal pressure of car 10through bypass valve line 36, filter 42, port 88, and port 90. Valve 100is unseated likewise at a pressure of 6 psi. to vent chamber 73 toatmosphere. Upon a reduction in the internal pressure of car 10 toaround p.s.i., for example, valve 100 will seat thereby effecting abuildup of pressure within chamber 73 which will likewise effeet aprompt seating of main diaphragm 64 on seat 62. Thus, a sensitivecontrol for efiecting a prompt seating of diaphragm 64 upon a reductionin pressure within car is provided. A suitable valve 34 may be purchasedcommercially from the Micromat Company, Hillsdale, NJ.

Filter 42 effectively filters the bypass air from the interior of car 10and prevents any large particles from entering the working mechanism ofvalve 34 thereby minimizing any clogging or malfunctioning of valve 34from lading or foreign matter in any of the working parts of valve 34.Filter 42 has been found to be highly effective and permits valve 34 tofunc tion efl'ectively under prolonged conditions of service.

What is claimed is:

1. In a fluid pressure relief structure for a covered hopper railway caradapted to be placed under internal fluid pressure for unloading finelydivided lading particles, said fluid pressure relief structurecomprising; a safety valve having a' main valve inlet communicating withthe interior of the car, a separate pilot line connected to said safetyvalve and in fluid connection with the interior of the car, said safetyvalve comprising a pair of spaced generally parallel diaphragms and afluid control chamber between the diaphragms, the pilot line being incommunication with the fluid control chamber, one of said diaphragmsbeing a main diaphragm normally seated across the main valve inlet andexposed directly to the interior of the car, a vent to atmosphere torelieve the pressure within the car upon unseating of the main diaphragmupon an excessive pressure within the car, and an additional vent toatmosphere responsive to the other of said diaphragms to relieve thefluid pressure within the fluid control chamber from the pilot line foreffecting a prompt reseating of said main diaphragm after the excessivepressure within the car has been vented to atmosphere by thefirst-mentioned vent; and filter means in said separate pilot line tominimize the passage of any finely divided lading particles to thesafety valve through the pilot line, said filter means comprising ahousing with an inlet and outlet connected to the pilot line, a filterelement within the housing through which the fluid in the pilot linepasses, said filter element having a micron rating between around 5 and25 and entrapping lading particles having a micron size greater than therating of the filter element.

i 4 i I!

1. In a fluid pressure relief structure for a covered hopper railway caradapted to be placed under internal fluid pressure for unloading finelydivided lading particles, said fluid pressure relief structurecomprising; a safety valve having a main valve inlet communicating withthe interior of the car, a separate pilot line connected to said safetyvalve and in fluid connection with the interior of the car, said safetyvalve comprising a pair of spaced generally parallel diaphragms and afluid control chamber between the diaphragms, the pilot line being incommunication with the fluid control chamber, one of said diaphragmsbeing a main diaphragm normally seated across the main valve inlet andexposed directly to the interior of the car, a vent to atmosphere torelieve the pressure within The car upon unseating of the main diaphragmupon an excessive pressure within the car, and an additional vent toatmosphere responsive to the other of said diaphragms to relieve thefluid pressure within the fluid control chamber from the pilot line foreffecting a prompt reseating of said main diaphragm after the excessivepressure within the car has been vented to atmosphere by thefirstmentioned vent; and filter means in said separate pilot line tominimize the passage of any finely divided lading particles to thesafety valve through the pilot line, said filter means comprising ahousing with an inlet and outlet connected to the pilot line, a filterelement within the housing through which the fluid in the pilot linepasses, said filter element having a micron rating between around 5 and25 and entrapping lading particles having a micron size greater than therating of the filter element.